PROBLEM TO BE SOLVED: To provide a differential caster suitable for an outer rotor type brushless motor, and an electric wheelchair.SOLUTION: The differential caster 41 includes a mounting plate 51; a steering shaft 53 rotatably supported to the mounting plate 51; a motor holder 101 provided at one end of the steering shaft 53 so as to intersect the steering shaft 53; a pair of wheels 136 supported on both axial end sides of the motor holder 101; and electric motors 100 built in the pair of wheels 136 respectively. A driving control substrate 120 for controlling driving of the electric motor 100 is disposed between the electric motor 100 and the steering shaft 53.